We report a vertical organic field effect transistor using a bilayer formed by sulfonated polyaniline (SPAN) film and a thin Aluminum layer as the intermediate electrode. The device uses p-Si as gate, SiO2 as gate insulator, SPAN/Al bilayer as drain, C60 fullerene as channel and Ag as the source (top electrode). This device works at low voltages driving high current densities for organic field effect transistors, between source and drain, of the order of microamperes, with the additional advantage that the modulation occurs at both negative and positive gate voltages.